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Chlorzoxazone

Generic Name: chlorzoxazone (klor ZOX a zone)
Brand Name: Lorzone, ...show all 8 brand names

Medically reviewed on Dec 5, 2017

What is chlorzoxazone?

Chlorzoxazone is a muscle relaxer that blocks pain sensations between the nerves and the brain.

Chlorzoxazone is used together with rest and physical therapy to treat skeletal muscle conditions such as pain or injury.

Chlorzoxazone may also be used for purposes not listed in this medication guide.

Important Information

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Before taking this medicine

You should not use chlorzoxazone if you are allergic to it.

To make sure chlorzoxazone is safe for you, tell your doctor if you have:

It is not known whether chlorzoxazone will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

It is not known whether chlorzoxazone passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Chlorzoxazone is not approved for use by anyone younger than 18 years old.

How should I take chlorzoxazone?

Follow all directions on your prescription label. Your doctor may occasionally change your dose. Do not use this medicine in larger or smaller amounts or for longer than recommended.

Chlorzoxazone is usually taken 3 or 4 times per day. Follow your doctor's dosing instructions very carefully.

Chlorzoxazone is only part of a complete program of treatment that may also include rest, physical therapy, or other pain relief measures. Follow your doctor's instructions.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include nausea, vomiting, diarrhea, severe drowsiness, headache, muscle weakness, shallow breathing, or fainting.

What should I avoid while taking chlorzoxazone?

Drinking alcohol with chlorzoxazone can cause side effects.

This medicine may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

Chlorzoxazone side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using this medicine and call your doctor at once if you have:

  • a light-headed feeling, like you might pass out;

  • skin rash, itching, or redness;

  • liver problems--stomach pain (upper right side), loss of appetite, vomiting, fever, unusual tiredness, dark urine, or jaundice (yellowing of the skin or eyes); or

  • signs of stomach bleeding--bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds.

Common side effects may include:

  • drowsiness;

  • dizziness; or

  • general ill feeling.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Chlorzoxazone dosing information

Usual Adult Dose for Muscle Spasm:

250 to 750 mg orally 3 to 4 times a day.

The dosage may be reduced as the condition of the patient improves.

Usual Pediatric Dose for Muscle Spasm:

125 to 500 mg orally 3 to 4 times a day.

Alternative dosing: 20 mg/kg/day in divided doses 3 to 4 times a day.

What other drugs will affect chlorzoxazone?

Taking chlorzoxazone with other drugs that make you sleepy or slow your breathing can cause dangerous side effects or death. Ask your doctor before taking a sleeping pill, narcotic pain medicine, prescription cough medicine, a muscle relaxer, or medicine for anxiety, depression, or seizures.

Other drugs may interact with chlorzoxazone, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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